text: The karyotype analysis and comparison of Chinese cabbage,Cabbage,Cauliflower,False pakchoi,Kailan and an interspecies hybrid between tetraploid False pakchoi and diploid Kailan were conducted in this paper.The results showed that the interspecies hybrid,including 2 genomes(AA) of False pakchoi and 1 genome(C) of Kailan,was a real allo-triploid(AAC).The average chromosome relative length of Cabbage,Cauliflower or Kailan was longer than that of Chinese cabbage or False pakchoi.However,the variance coefficient of the relative length of the Chinese cabbage or False pakchoi was bigger than Cabbage,Cauliflower or Kailan.The karyotype of Chinese cabbage and False pakchoi belong to 2B type,Cauliflower and Kailan 2A type,and Cabbage 3A type.